Tuesday, January 20, 2015

Update - January 20, 2015

In the post I did on the 16th (click here), I discussed the upcoming couple of weeks and forcing from the MJO (Madden Julian Oscillation).  With that forcing would likely be a relatively mild period with a few cooler periods offset by very mild days.  So far, that has worked out.

Also, I mentioned relatively dry weather across the high plains and if there was precipitation it would be minor.  Overnight Monday and early this morning (Tuesday) there was an area of light rain (and snow at higher elevations of the plains) that moved east across Kansas.  Amounts were generally light (less than a 10th of an inch or nothing at all) but there were a couple of 2 inch snow reports near Goodland and points west.

But what I didn't see coming (and perhaps should have) was the system that could break underneath the upper level ridge that has been parked across the west coast.  That weather system is now showing up on today's satellite image.  The X over California denotes the upper levels of the system and it is wet and headed east!

First, the upper system that brought the rain early this Tuesday morning was located across southeast Missouri by Tuesday afternoon.  Another system (X across Montana) will combine with the California system to produce widespread snow Wednesday and Thursday across southern Colorado, far southwest KS, New Mexico and the Texas Panhandle.

The Weather Prediction Center has the following forecast for possible amounts.  That is a pretty robust forecast!  Eventually the system will bring rain to Oklahoma and the remainder of Texas and into the southeast U.S.

Friday, January 16, 2015

Rest of the winter and into the summer - Updated 1/16/15

For those that have followed this blog, I apologize that I haven't updated it since the 28th of December.  Unfortunately my mother passed away unexpectedly on the 2nd and I've been consumed by life's challenges.

In the post on the 28th of December (click here), I discussed a very significant Arctic intrusion that was expected.  Obviously that did verify with the coldest temperatures we've seen in quite a while being observed.  In addition, surface pressures reached record levels at many locations (for December).  That type of cold is likely to return later in February, but I'll discuss that further down in the blog.  With the pattern discussed in the previous blog, it did also bring several rounds of snow.  The most significant occurred on the 3rd of January.

 This Arctic air intrusion is the 3rd major one of the winter (although the first technically wasn't in winter - as you might recall it was around November 11th).  Since November 17, 2015 much of the eastern 2/3 of the country has had below normal temperatures, on average.  And this DOES NOT include that major Arctic outbreak in November!  Yes there has been "mild" periods (as had been expected) but the colder periods have been more severe and has offset the milder conditions.  The map below shows the departure from normal for the past 60 days (11/17/14 to 1/15/15)...

and for precipitation

Notice how wet it has been across parts of California?  That was the result of ONLY about a 2 week period back in December but there really hasn't been much since. Look up there in Montana and Wyoming.  WOW!  The snowpack is getting pretty deep up there which could result in some spring flooding down the Missouri.

Here is a look at the current drought situation:

El Niño or La Nina

El Niño is the warm phase of the El Niño Southern Oscillation (commonly referred to as ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific. An El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. The cool phase of ENSO is called "La Niña" with SST in the eastern Pacific below average and air pressures high in the eastern and low in western Pacific

Back in the summer months there were MANY "experts" claiming a Super El Nino would be coming for the winter.   A so called Super El Nino would be one with a very large anomaly on the warm side.  That type, like what occurred back in the 80s, would normally bring flooding rains from California to Florida.  Some folks, me included, had doubts that a full fledged El Nino would even form and if it did would be weak.  (you can look back at previous posts in this blog) So,what has happened?  It's barely been an El Nino event.  Looking at the Southern Oscillation Index (which can chart and El Niño or it's sister La Nina) there is indications that this very weak El Niño may already be waning.

In the chart above, for an El Niño the index needs to be consistently less than -10 for at least 3 months.  The green line is a 90 day average.  Do you see the trend going back towards the positive?

Ok, so big deal, right?  Well lets look at the following map that shows what the jet stream and sensible weather does (normally) during an El Niño or La Nina.  Keep in mind it's just a composite of events so there are caveats.  

The northern hemispheric wind patterns and sensible weather across the United States has been any BUT an El Niño pattern.   In fact, it more closely resembles a La Nina pattern. So in essence what I'm saying is the wind patterns have been more La Nina like in an El Niño forcing environment.  Confusing I'm sure.   Suffice it to say that one CANNOT predict the weather based solely on ENSO.

So now what?  Well, one of the forcing areas for our weather (even with or without ENSO) is what comes out of the Maritime Continents of the southwest Pacific.  It is called the Madden Julian Oscillation (MJO).  Currently there is a rather coherent signal from a pretty good MJO that is moving across the central Pacific.  The MJO takes about 45-60 days or so to develop and dissipate as it moves east and then southeast across the equator. 

The center of the MJO is denoted on the following map by the big X.  The upper wind field is denoted by the green arrows and is mirrored across the equator.

Currently the forcing is going into what is called the warm phase (6 and 7) and indeed the forcing is being realized across much of the country, including the central plains.  Temperatures as of Friday afternoon were in the 60s across a large part of the area.  I'm expecting, in general, above average temperatures for the next 2 weeks, but with a brief period or two of colder weather.

Along with the warmer weather, it will be mostly dry across the high plains.  There could be a weak system that could bring some precipitation but if so, it would be minimal. 

Changes are then expected towards the end of the month, say sometime after the 23/24th.  It looks like the high plains will go into a more active pattern the last part of the month and into February.  Although an Arctic outbreak is not expected during this period, there will be much colder air (just not severe Arctic) I would bet there will be several high impact storms. As time closes in I will surely update with later thoughts.

By the 10th-15th of February (probably closer to the 15th) I believe there is a high probability of another major Arctic air outbreak.  This time I would suspect we might see temperatures as cold and maybe even colder than this last one.

Then for the remainder of the winter there will likely be several warm/mild periods followed by more cold. I'm guessing at this point that a late spring freeze will be probable along with a late season blizzard somewhere across the central high plains.  There will also be windy and dry periods too.  As we get later into March and April I would expect several strong cold fronts with high winds and probably episodes of blowing dirt - not good for the winter wheat.

Beyond early spring and into the summer I'll just offer what the "official" outlook is from the Climate Prediction Center and NOAA.  Later this month or by early February I will give my own personal take on it.  Early thinking is the precipitation outlook "may" be optimistic.

Temperatures - the average for January-February-March

Precipitation - the average for January-February-March

Temperatures - the average for March - April - May

Precipitation - the average for March - April - May

Temperatures - the average for June - July - August (Summer)

Precipitation - the average for June - July - August (Summer)